Leaking Brake Fluid Near Left Rear Wheel - 94 Previa 2WD

[josephwilcox]

Hey All- So I have a brake fluid leak near my left rear wheel. It was only leaking a tiny bit for a bit so I would just put in some fluid every month or so, but it is leaking much worse now. I have done some searching and it seems like it is either a brake line or hose. I got under there to see what happened when the brake pedal was depressed but couldn't see a specific leak. I did notice some kind of part that most of the fluid seems to be leaking out of. This is a picture of it:

Screen shot 2015-04-19 at 10.48.54 AM.jpg

There was not a similar part on the passenger side so I thought this might be something unique and could be leaking from it. Any ideas?

Thanks in advance.

[timsrv]

Hi & welcome to TVT! That's your LSP&BV (Load Sensing Proportioning & By-pass Valve). It's purpose is to increase/decrease pressure to your rear brakes depending on how much weight is on the rear axle. Unfortunately it's an expensive part and it's also Previa Specific. This means your only choice for replacement will likely be OEM Toyota or perhaps a salvage yard. These valves are specific to the type of rear brakes you have. For rear disc brakes it's Toyota Part #47900-28313. For rear drum brakes it's Toyota Part #47900-28201. Your average stealership will want over $300 for this part. Some of the on-line discount Toyota parts sites will want around $230 (plus shipping). Tim

[josephwilcox]

Thanks for the reply Tim. After doing some research, I thought it was most likely the LSP&BV so I'm glad you confirmed that suspicion. I did get a little further under there and actually saw the part, it looks to be in real rough shape, very rusty. It looks like the fluid is coming out where one of the lines goes into the LSP&BV. Do you know, is there a chance the issue might be with the brake line and if I swapped the line out, it might fix the issue? Otherwise I'll have to bite the bullet on the part.

Appreciate the help.

[timsrv]

There's always a chance, but I'd consider it slim. It sounds like it's leaking enough to verify actual spot. Just have somebody stand on the brake pedal while you inspect. Tim

[josephwilcox]

There's always a chance, but I'd consider it slim. It sounds like it's leaking enough to verify actual spot. Just have somebody stand on the brake pedal while you inspect. Tim

Do some people replace those with some kind of T-fitting? If so, do you have any knowledge of that? I'm assuming this would end up sending 50/50 braking power between the front and rears, which I understand could be a bit dangerous, but for $300 I might be willing to take the risk.

Thanks.

[timsrv]

Don't put a tee here. Due to physics, when you slam on the brakes the weight shifts to the front wheels. For this reason (and weight distribution) all cars have proportioning valves for the rear brakes. Only some trucks, vans, and a hand-full of SUV's have the load sensing feature.

It's a safety device. If the rears get too much pressure they can lock up during a moderate to harsh stop, and this can cause fish tailing and/or complete loss of control. Because the need for such a device (proportioning valve) is universal, it's very possible one from another vehicle may interchange (but it might be like finding a needle in a haystack). If you always drive with a set weight (no major changes in loading/unloading), another possible option is to forget about the "load sensing" feature of the Previa valve and go with an adjustable valve (proportioning only). Adjustable valves (set it, forget it) are made and sold for project cars for under $100. Of course there would be some other parts/adapters required and perhaps some special tools to adapt to the Previa. After all that, you'd need to accurately adjust to deliver the correct proportions to the rear brakes (should be done with a pressure gauge). After all that, it still wouldn't self adjust/compensate (like the original) when the van was loaded heavy. Considering all that, a measly $300 for the correct part doesn't sound all that bad.

There's always salvage yards. I'm not sure about your area, but here there's Previas in all the Pick-N-Pulls. I'm guessing they'd sell you this for under $20. If you go that route, you may want to tell them it's a clutch part. I'm not sure what the rules are for parts like this (I don't buy used brake parts), but not sure if they'll sell you something they know is for brakes. One thing I notice is they intentionally break (destroy) master cylinders in pretty much every vehicle in the yards around here, so that makes me wonder about their policy on brake parts. Tim

[josephwilcox]

Right on, thanks so much Tim, she will be back on the road in no time.